Three-phase reactor comprising iron-core units and coils

ABSTRACT

A three-phase reactor includes: an outer peripheral iron core; and at least three iron-core coils that come in contact with an inner surface of the outer peripheral iron core or are joined to the inner surface. The at least three iron-core coils include corresponding iron cores and corresponding coils wound around the iron cores, and gaps that can magnetically connect one iron-core coil of the at least three iron-core coils and an iron-core coil adjacent to the one iron-core coil to each other are formed between the one iron-core coil of the at least three iron-core coils and the iron-core coil adjacent to the one iron-core coil.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/400,066, filed Jan. 6, 2017, which claims priority to JapaneseApplication No. 2016-160747, filed Aug. 18, 2016, and JapaneseApplication No. 2016-014484, filed Jan. 28, 2016, the teachings of whichare herein incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a three-phase reactor includingiron-core units and coils.

2. Description of the Related Art

Ordinarily, three-phase reactors include three iron cores and threecoils wound around the iron cores. Japanese Unexamined PatentPublication (Kokai) No. 2-203507 discloses a three-phase reactorincluding three coils placed side by side. International Publication No.WO 2014/033830 discloses that the corresponding central axes of pluralcoils are arranged around the central axis of a three-phase reactor.Japanese Unexamined Patent Publication (Kokai) No. 2008-177500 disclosesa three-phase reactor including plural straight magnetic cores that areradially arranged, connecting magnetic cores that connect the straightmagnetic cores, and coils that are wound around the straight magneticcores and the connecting magnetic cores.

SUMMARY OF THE INVENTION

A three-phase alternating current passes through a coil in each phase ofa three-phase reactor. In the three-phase reactor that is conventional(Japanese Unexamined Patent Publication (Kokai) No. 2-203507), thelength of a magnetic path through which magnetism generated whencurrents pass through coils in two optional phases passes may depend onthe combination of the phases. Accordingly, there has been a problemthat even when three-phase alternating currents in equilibrium arepassed through the corresponding phases of a three-phase reactor, thedensities of magnetic fluxes passing through iron cores in thecorresponding phases are different from each other, and inductances arealso imbalanced.

In the three-phase reactor that is conventional (Japanese UnexaminedPatent Publication (Kokai) No. 2-203507), it may be impossible tosymmetrically arrange iron-core coils in corresponding phases.Therefore, magnetic fluxes generated from the iron-core coils causeimbalanced inductances. When inductances are imbalanced in a three-phasereactor as described above, it is impossible to ideally output athree-phase alternating current even if the three-phase alternatingcurrent is ideally inputted.

In the three-phase reactors that are conventional (Japanese UnexaminedPatent Publication (Kokai) No. 2-203507 and International PublicationNo. WO 2014/033830), the dimensions of gaps (thicknesses of gaps) dependon the dimensions of a commercially available gap member. Therefore, thewinding number and cross-sectional area of a coil may be limited by thedimension of a gap member when the structure of a three-phase reactor isdetermined. The precision of inductances in a three-phase reactordepends on the precision of the thickness of a gap member. Because theprecision of the thickness of a gap member is commonly around ±10%, theprecision of inductances in a three-phase reactor also depends thereon.It is also possible to produce a gap member having a desired dimensionwhile the cost of the gap member is increased.

In order to assemble a three-phase reactor, a step of assembling thecore members of the three-phase reactor on a one-by-one basis, and astep of connecting some core members to each other are preferablyperformed several times. Therefore, there is a problem that it isdifficult to control the dimension of a gap. In addition, amanufacturing cost is increased by improving the precision of thethickness of a gap member.

A core member is ordinarily formed by layering plural steel sheets forlayering. A three-phase reactor preferably has a portion in which coremembers come in contact with each other. In addition, it is preferableto alternately layer the steel sheets for layering in order to enhancethe precision of the contact portion. Such operations have been verycomplicated.

Further, the three-phase reactors that are conventional (JapaneseUnexamined Patent Publication (Kokai) No. 2-203507 and InternationalPublication No. WO 2014/033830) have a problem that a magnetic fieldleaks out to an air area around a coil in such a three-phase reactorbecause the coil is exposed to the outside. The magnetic field that hasleaked out can influence a heart pacemaker, and can heat a magneticsubstance around such a three-phase reactor. In recent years,amplifiers, motors, and the like have tended to be driven byhigher-frequency switching. Therefore, the frequency of high-frequencynoise can also become higher. Thus, it is also conceivable that theinfluence of the magnetic field that has leaked out on the outsidebecomes greater.

Further, the three-phase reactors that are conventional (JapaneseUnexamined Patent Publication (Kokai) No. 2-203507 and InternationalPublication No. WO 2014/033830) have a problem that a magnetic flux thathas leaked out of a gap causes an eddy-current loss in a coil, therebyincreasing the loss of the coil, because the coil is arranged close tothe gap. A method of making a structure in which the coil is locatedaway from the gap can be provided in order to solve the problem.However, the method has a demerit that a weight and a cost are increasedbecause the core and the winding diameter of the coil become large.

The problem that the inductances are imbalanced can be solved byenlarging only the gap of a central phase. However, a magnetic field isallowed to further leak out by enlarging the gap.

Further, in the reactors having the conventional structures (JapaneseUnexamined Patent Publication (Kokai) No. 2-203507 and InternationalPublication No. WO 2014/033830), the temperatures of a coil and a corehave tended to easily become unbalanced because of high thermalresistance between the coil and the core. In order to eliminate theunbalance between the temperatures, the entire coil may be molded withresin to bring the coil into intimate contact with the core. However,there is a problem that a cost is increased. Further, in order tosuppress noise generated from a gap, design can be performed such that amagnetic flux density is reduced, and molding with resin can beperformed as described above. However, there is also a problem that acost is increased.

Methods for solving the above-described problems of the imbalance ininductances, the leakage of a magnetic field due to a coil exposed tothe outside, and a gap dimension also include such a technique asdescribed in Japanese Unexamined Patent Publication (Kokai) No.2008-177500. It is described that inductances can be offered bysupplying a current to a control winding without disposing a gap in thetechnique. However, the technique has a problem that a control circuitfor controlling a current passed through the control winding isdemanded, whereby an unnecessary power is consumed by the controlwinding. Further, the technique also has a problem that a magnetic fieldgenerated from the control winding leaks out to an area around thecontrol winding because the control winding is exposed to the outside.

The present invention was accomplished under such circumstances with anobject to provide a three-phase reactor with gaps, which inhibitsinductances from being imbalanced and a magnetic field from leaking outto the outside, and in which a control winding is unnecessary, and aloss caused by a leakage flux can be reduced.

In order to achieve the object described above, according to a firstaspect of the present invention, there is provided a three-phase reactorincluding: an outer peripheral iron core; and at least three iron-corecoils that come in contact with an inner surface of the outer peripheraliron core or are joined to the inner surface, wherein the at least threeiron-core coils include corresponding iron cores and corresponding coilswound around the iron cores; and gaps that can magnetically connect oneiron-core coil of the at least three iron-core coils and an iron-corecoil adjacent to the one iron-core coil to each other are formed betweenthe one iron-core coil of the at least three iron-core coils and theiron-core coil adjacent to the one iron-core coil.

According to a second aspect of the present invention, the number of theat least three iron-core coils is a multiple of 3 in the first aspect ofthe present invention.

According to a third aspect of the present invention, the iron cores ofthe at least three iron-core coils include plural iron-core units; andiron-core unit gaps that can magnetically connect the plural iron-coreunits are formed between the plural iron-core units in either the firstor second aspect of the present invention.

According to a fourth aspect of the present invention, outer peripheraliron-core gaps that can magnetically connect the iron cores of the atleast three iron-core coils and the outer peripheral iron core to eachother are formed between the iron cores of the at least three iron-corecoils and the outer peripheral iron core in any of the first to thirdaspects of the present invention.

According to a fifth aspect of the present invention, the outerperipheral iron core includes plural outer peripheral iron-core units inany of the first to fourth aspects of the present invention.

According to a sixth aspect of the present invention, outer peripheraliron-core unit gaps are formed between outer peripheral iron-core units,adjacent to each other, of the plural outer peripheral iron-core unitsin the fifth aspect of the present invention.

According to a seventh aspect of the present invention, the at leastthree iron-core coils are rotationally symmetrically arranged in any ofthe first to sixth aspects of the present invention.

According to an eighth aspect of the present invention, the three-phasereactor includes: a first set including at least three iron-core coils;and a second set including at least three other iron-core coils in anyof the first to seventh aspects of the present invention.

According to a ninth aspect of the present invention, the three-phasereactor includes not less than three sets, each of which includes threeiron-core coils in the eighth aspect of the present invention.

According to a tenth aspect of the present invention, a gap member,insulating paper, or resin which is a non-magnetic material is insertedor filled into the gaps of the three-phase reactor in any of the firstto ninth aspects of the present invention.

According to an eleventh aspect of the present invention, a gap member,insulating material, or resin which is a non-magnetic material is filledinto an inside of the outer peripheral iron core of the three-phasereactor in any of the first to ninth aspects of the present invention.

According to a twelfth aspect of the present invention, there isprovided a three-phase reactor including: an outer peripheral iron core;and at least three iron-core coils that come in contact with an innersurface of the outer peripheral iron core or are joined to the innersurface, wherein the at least three iron-core coils includecorresponding iron cores and corresponding coils wound around the ironcores; the three-phase reactor further includes inter-coil iron coresarranged between the at least three iron-core coils; and gaps that canmagnetically connect the at least three iron-core coils and theinter-coil iron cores to each other are formed between the at leastthree iron-core coils and the inter-coil iron cores.

According to a thirteenth aspect of the present invention, each of theinter-coil iron cores includes two surfaces making an acute angle witheach other; and the two surfaces face the corresponding iron-core coilsacross the corresponding gaps in the twelfth aspect of the presentinvention.

According to a fourteenth aspect of the present invention, the number ofthe at least three iron-core coils is a multiple of 3 in either thetwelfth or thirteenth aspect of the present invention.

According to the fifteenth aspect of the present invention, the ironcores of the at least three iron-core coils include plural iron-coreunits; and iron-core unit gaps that can magnetically connect the pluraliron-core units are formed between the plural iron-core units in any ofthe twelfth to fourteenth aspects of the present invention.

According to a sixteenth aspect of the present invention, outerperipheral iron-core gaps that can magnetically connect the iron coresof the at least three iron-core coils and the outer peripheral iron coreare formed between the iron cores of the at least three iron-core coilsand the outer peripheral iron core in any of the twelfth to fifteenthaspects of the present invention.

According to a seventeenth aspect of the present invention, theinter-coil iron cores include plural inter-coil iron-core units; andinter-coil iron-core unit gaps that can magnetically connect the pluralinter-coil iron-core units are formed between the plural inter-coiliron-core units in any of the twelfth to sixteenth aspects of thepresent invention.

According to an eighteenth aspect of the present invention, the outerperipheral iron core includes plural outer peripheral iron-core units inany of the twelfth to seventeenth aspects of the present invention.

According to a nineteenth aspect of the present invention, outerperipheral iron-core unit gaps are formed between outer peripheraliron-core units, adjacent to each other, of the plural outer peripheraliron-core units, in the eighteenth aspect of the present invention.

According to a twentieth aspect of the present invention, the threeiron-core coils are rotationally symmetrically arranged in any of thetwelfth to nineteenth aspects of the present invention.

According to a twenty-first aspect of the present invention, thethree-phase reactor includes: a first set including three iron-corecoils; and a second set including three other iron-core coils in any ofthe twelfth to twentieth aspects of the present invention.

According to a twenty-second aspect of the present invention, thethree-phase reactor includes not less than three sets, each of whichincludes three iron-core coils in the twenty-first aspect of the presentinvention.

According to a twenty-third aspect of the present invention, a gapmember, insulating paper, or resin which is a non-magnetic material isinserted or filled into the gaps of the three-phase reactor in any ofthe twelfth to twenty-second aspects of the present invention.

According to a twenty-fourth aspect of the present invention, a gapmember, insulating material, or resin which is a non-magnetic materialis filled into an inside of the outer peripheral iron core of thethree-phase reactor in any of the twelfth to twenty-second aspects ofthe present invention.

According to a twenty-fifth aspect of the present invention, there isprovided a motor driving device including the reactor according to anyof the first to twenty-fourth aspects of the present invention.

According to a twenty-sixth aspect of the present invention, there isprovided a machine including the motor driving device according to thetwenty-fifth aspect of the present invention.

According to a twenty-seventh aspect of the present invention, there isprovided a power conditioner including the reactor according to any ofthe first to twenty-fourth aspects of the present invention.

According to a twenty-eighth aspect of the present invention, there isprovided a machine or device including the power conditioner accordingto the twenty-seventh aspect of the present invention.

The objects, features, and advantages as well as other objects,features, and advantages of the present invention will become clear dueto detailed descriptions of exemplary embodiments of the presentinvention illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top face view of a three-phase reactor according to a firstembodiment of the present invention;

FIG. 1B is a cross-sectional view of the three-phase reactor illustratedin FIG. 1A;

FIG. 1C is a perspective view of the three-phase reactor illustrated inFIG. 1A;

FIG. 2 is a cross-sectional view of a three-phase reactor according to asecond embodiment of the present invention;

FIG. 3A is a cross-sectional view of a three-phase reactor according toa third embodiment of the present invention;

FIG. 3B is a cross-sectional view of another three-phase reactoraccording to the third embodiment of the present invention;

FIG. 4 is a cross-sectional view of a three-phase reactor according to afourth embodiment of the present invention;

FIG. 5 is a cross-sectional view of a three-phase reactor according to afifth embodiment of the present invention;

FIG. 6 is a cross-sectional view of a three-phase reactor according to asixth embodiment of the present invention;

FIG. 7 is a cross-sectional view of a three-phase reactor according to aseventh embodiment of the present invention;

FIG. 8 is a cross-sectional view of a three-phase reactor according toan eighth embodiment of the present invention;

FIG. 9 is a cross-sectional view of a three-phase reactor according to aninth embodiment of the present invention;

FIG. 10 is a cross-sectional view of a three-phase reactor according toa tenth embodiment of the present invention;

FIG. 11 is a cross-sectional view of a three-phase reactor according toan example of the present invention;

FIG. 12 is a top face view of a three-phase reactor according to anotherexample of the present invention;

FIG. 13A is a top face view of a conventional three-phase reactor;

FIG. 13B is a view illustrating magnetic fluxes in the three-phasereactor illustrated in FIG. 13A;

FIG. 13C is a partially enlarged view of FIG. 13B;

FIG. 14A is a cross-sectional view of a three-phase reactor according toan eleventh embodiment of the present invention;

FIG. 14B is a perspective view of the three-phase reactor illustrated inFIG. 14A;

FIG. 14C is a view illustrating magnetic fluxes in the three-phasereactor illustrated in FIG. 14A;

FIG. 14D is a partially enlarged view of FIG. 14C;

FIG. 15A is a view illustrating an alternative example in the eleventhembodiment of the present invention;

FIG. 15B is a view illustrating another alternative example in theeleventh embodiment of the present invention;

FIG. 15C is a view illustrating still another alternative example in theeleventh embodiment of the present invention;

FIG. 16A is a cross-sectional view of a three-phase reactor according toa twelfth embodiment of the present invention;

FIG. 16B is a view illustrating magnetic fluxes in the three-phasereactor illustrated in FIG. 16A;

FIG. 16C is a partially enlarged view of FIG. 16B;

FIG. 17 is a cross-sectional view of a three-phase reactor according toa thirteenth embodiment of the present invention;

FIG. 18A is a cross-sectional view of a three-phase reactor according toa fourteenth embodiment of the present invention;

FIG. 18B is a cross-sectional view of another three-phase reactoraccording to the fourteenth embodiment of the present invention;

FIG. 18C is a cross-sectional view of still another three-phase reactoraccording to the fourteenth embodiment of the present invention;

FIG. 19 is a cross-sectional view of a three-phase reactor according toa fifteenth embodiment of the present invention;

FIG. 20 is a cross-sectional view of a three-phase reactor according toa sixteenth embodiment of the present invention;

FIG. 21 is a cross-sectional view of a three-phase reactor according toa seventeenth embodiment of the present invention;

FIG. 22 is a cross-sectional view of a three-phase reactor according toan eighteenth embodiment of the present invention;

FIG. 23 is a cross-sectional view of a three-phase reactor according toa nineteenth embodiment of the present invention;

FIG. 24A is a cross-sectional view of a three-phase reactor according tostill another embodiment of the present invention;

FIG. 24B is a cross-sectional view of another three-phase reactoraccording to still another embodiment of the present invention;

FIG. 25 is a cross-sectional view of a three-phase reactor according tostill another embodiment of the present invention;

FIG. 26 is a view illustrating a machine or device including athree-phase reactor of the present invention; and

FIG. 27 is a view illustrating another machine or device including athree-phase reactor of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will be described below withreference to the accompanying drawings. In the following drawings,similar members are denoted by similar reference characters. Thereduction scales of the drawings are varied as appropriate in order tofacilitate understanding.

FIG. 1A is a top face view of a three-phase reactor according to a firstembodiment of the present invention. Further, FIG. 1B is across-sectional view of the three-phase reactor illustrated in FIG. 1A,and FIG. 1C is a perspective view of the three-phase reactor illustratedin FIG. 1A.

As illustrated in FIG. 1A, FIG. 1B, and FIG. 1C, a three-phase reactor 5includes: an outer peripheral iron core 20; and three iron-core coils 31to 33 of which each is magnetically connected to the outer peripheraliron core 20. In FIG. 1A, the iron-core coils 31 to 33 are arranged inthe inside of the outer peripheral iron core 20 having a ring shape. Theiron-core coils 31 to 33 are spaced from each other circumferentially atregular intervals in the three-phase reactor 5.

As can be seen from the drawings, the iron-core coils 31 to 33 include:corresponding iron cores 41 to 43 that radially extend; andcorresponding coils 51 to 53 wound around the iron cores. The radiallyouter end of each of the iron cores 41 to 43 comes in contact with theouter peripheral iron core 20, or is formed integrally with the outerperipheral iron core 20.

Further, the radially inner end of each of the iron cores 41 to 43 islocated in the vicinity of the center of the outer peripheral iron core20. In FIG. 1A and the like, the radially inner end of each of the ironcores 41 to 43 converges toward the center of the outer peripheral ironcore 20, and the front end angle of the radially inner end is about 120degrees. The radially inner ends of the iron cores 41 to 43 are spacedfrom each other through gaps 101 to 103 that can magnetically connectthe radially inner ends to each other.

In other words, in the first embodiment, the radially inner end of theiron core 41 is spaced from each of the radially inner ends of the twoadjacent iron cores 42, 43 through each of the gaps 101, 102. The samealso applies to the other iron cores 42, 43. The dimensions of the gaps101 to 103 are intended to be equal to each other. In embodimentsdescribed later, illustrations of the gaps 101 to 103 may be omitted.

The three-phase reactor 5 can be formed to be lightweight and simplebecause a central iron core located in the center of the three-phasereactor 5 is unnecessary in the present invention as described above.Further, the three iron-core coils 31 to 33 are surrounded by the outerperipheral iron core 20, and therefore, a magnetic field generated fromthe coils 51 to 53 does not leak out to the outside of the outerperipheral iron core 20. Further, the gaps 101 to 103 having optionalthicknesses can be inexpensively disposed, and therefore, the reactor ismore advantageous in view of design than reactors having conventionalstructures.

Further, differences in magnetic path lengths between phases in thethree-phase reactor 5 of the present invention become less than those inthe reactors having the conventional structures. Therefore, in thepresent invention, an imbalance in inductances caused by the differencesin the magnetic path lengths can be reduced.

FIG. 2 is a cross-sectional view of a three-phase reactor according to asecond embodiment of the present invention. A three-phase reactor 5illustrated in FIG. 2 includes: an outer peripheral iron core 20; andiron-core coils 31 to 36, each of which is magnetically connected to theouter peripheral iron core 20, and which are similar to those describedabove. The iron-core coils 31 to 36 include: corresponding iron cores 41to 46 that radially extend; and corresponding coils 51 to 56 woundaround the iron cores.

The front end angle of the radially inner end of each of the iron cores41 to 46 of the three-phase reactor 5 illustrated in FIG. 2 is about 60degrees. The radially inner ends of the iron cores 41 to 46 are spacedfrom each other through gaps 101 to 106 that can magnetically connectthe radially inner ends to each other. As described above, thethree-phase reactor 5 may include the iron-core coils 31 to 36 of whichthe number is a multiple of 3.

It is obvious that effects that are generally similar to the effectsdescribed above can also be obtained in the second embodiment. Further,in the second embodiment, the number of the iron-core coils 31 to 36 isintended to be a multiple of 3, and therefore, plural iron-core coilsexist for one phase. The cross-sectional area of each of the iron-corecoils can be reduced by connecting the plural iron-core coils inparallel to each other.

FIG. 3A is a cross-sectional view of a three-phase reactor according toa third embodiment of the present invention. Iron cores 41 to 43 thatradially extend in iron-core coils 31 to 33 in a three-phase reactor 5illustrated in FIG. 3A include first iron-core units 41 a to 43 a thatare located in radially internal sides, and second iron-core units 41 bto 43 b that are located in radially external sides, respectively.Iron-core unit gaps 111 to 113 that can magnetically connect the firstiron-core units 41 a to 43 a and the second iron-core units 41 b to 43 bare formed between the first iron-core units 41 a to 43 a and the secondiron-core units 41 b to 43 b. Further, the three-phase reactor 5includes coils 51 to 53 that are wound around both the first iron-coreunits 41 a to 43 a and the second iron-core units 41 b to 43 b,respectively.

Further, FIG. 3B is a cross-sectional view of another three-phasereactor according to the third embodiment of the present invention. Ironcores 41 to 43 that radially extend in iron-core coils 31 to 33 includefirst iron-core units 41 a to 43 a that are located in radially internalsides, and second iron-core units 41 b to 43 b that are located inradially external sides, respectively. Iron-core unit gaps 111 to 113that can magnetically connect the first iron-core units 41 a to 43 a andthe second iron-core units 41 b to 43 b are formed between the firstiron-core units 41 a to 43 a and the second iron-core units 41 b to 43b. Further, a three-phase reactor 5 includes first coils 51 a to 53 athat are wound around the first iron-core units 41 a to 43 a, and secondcoils 51 b to 53 b that are wound around the second iron-core units 41 bto 43 b.

In other words, in the embodiments illustrated in FIG. 3A and FIG. 3B,each of the iron cores 41 to 43 includes the two iron-core unitsarranged in a single row. Each of the iron-core coils 31 to 33 includesthe iron-core unit gaps 111 to 113 formed between the iron-core units.

In the embodiments illustrated in FIG. 3A and FIG. 3B, iron-core unitgaps 111 to 113 as well as the gaps 101 to 103 are formed, andtherefore, the dimensions of the gaps and iron-core unit gaps includedin the iron-core coils 31 to 33 can be reduced. Further, magnetic fluxesleaking out of the gaps 101 to 103 and the iron-core unit gaps 111 to113 can be reduced. It will be appreciated that each of the iron cores41 to 43 may include three or more iron-core units arranged in a singlerow.

FIG. 4 is a cross-sectional view of a three-phase reactor according to afourth embodiment of the present invention. Iron-core coils 31 to 33 ina three-phase reactor 5 illustrated in FIG. 4 includes: iron cores 41′to 43′ that radially extend; and coils 51 to 53 wound around the ironcores. Like the embodiments described above, the radially inner ends ofthe iron cores 41′ to 43′ are adjacent to each other through gaps 101 to103.

In the fourth embodiment, corresponding outer peripheral iron-core gaps121 to 123 that can magnetically connect the radially outer ends of theiron cores 41′ to 43′ and an outer peripheral iron core 20 to each otherare formed between the radially outer ends of the iron cores 41′ to 43′and an outer peripheral iron core 20. Heat is generated in the iron-corecoils 31 to 33 when the three-phase reactor 5 is operated. The fourthembodiment has the effect of inhibiting heat generated from theiron-core coils 31 to 33 from being transferred to the outer peripheraliron core 20 because the outer peripheral iron-core gaps 121 to 123 areformed.

FIG. 5 is a cross-sectional view of a three-phase reactor according to afifth embodiment of the present invention. Iron-core coils 31 to 33 in athree-phase reactor 5 illustrated in FIG. 5 are generally similar tothose described with reference to FIG. 1. In the fifth embodiment, anouter peripheral iron core 20 includes plural, for example, three outerperipheral iron-core units 21 to 23 having an arc shape. In FIG. 5, theouter peripheral iron-core unit 21 comes in contact with an iron core41, or is formed integrally with the iron core 41. Similarly, the outerperipheral iron-core units 22, 23 come in contact with iron cores 42,43, or are formed integrally with the iron cores 42, 43, respectively.In the embodiment illustrated in FIG. 5, the outer peripheral iron core20 can be easily manufactured even when the outer peripheral iron core20 is large.

FIG. 6 is a cross-sectional view of a three-phase reactor according to asixth embodiment of the present invention. In the sixth embodiment, anouter peripheral iron-core unit gap 61 that can magnetically connect anouter peripheral iron-core unit 21 and an outer peripheral iron-coreunit 22 is formed between the outer peripheral iron-core unit 21 and theouter peripheral iron-core unit 22. Similarly, outer peripheraliron-core unit gaps 62, 63 that can magnetically connect an outerperipheral iron-core unit 22 and an outer peripheral iron-core unit 23,and an outer peripheral iron-core unit 23 and an outer peripheraliron-core unit 21, respectively, are formed between the outer peripheraliron-core unit 22 and the outer peripheral iron-core unit 23, andbetween the outer peripheral iron-core unit 23 and the outer peripheraliron-core unit 21, respectively.

In other words, each of the outer peripheral iron-core units 21 to 23 isarranged through each of the outer peripheral iron-core unit gaps 61 to63. In such a case, the outer peripheral iron-core unit gaps 61 to 63can be adjusted by adjusting the lengths of the outer peripheraliron-core units 21 to 23. It is obvious that as a result, an imbalancein inductances in three-phase reactor 5 can be adjusted.

A three-phase reactor 5 illustrated in FIG. 6 differs from thethree-phase reactor 5 illustrated in FIG. 5 only in view of having theouter peripheral iron-core unit gaps 61 to 63. In other words, the outerperipheral iron-core unit gaps 61 to 63 are not formed between theadjacent outer peripheral iron-core units 21 to 23 in the fifthembodiment. In the embodiments illustrated in FIG. 5 and FIG. 6, theouter peripheral iron core 20 can be easily manufactured even when theouter peripheral iron core 20 is large.

FIG. 7 is a cross-sectional view of a three-phase reactor according to aseventh embodiment of the present invention. Because a three-phasereactor 5 illustrated in FIG. 7 is generally similar to the three-phasereactor 5 illustrated in FIG. 2, detailed descriptions of thethree-phase reactor 5 are omitted. In FIG. 7, the dimensions ofcorresponding iron cores 41 to 46 and coils 51 to 56 in iron-core coils31 to 36 as well as gaps 101 to 106 are equal to each other.

Further, the iron-core coils 31 to 36 are arranged rotationallysymmetrically in the three-phase reactor 5. Therefore, it is obviousthat an imbalance in inductances caused by the arrangement of the sixiron-core coils 31 to 36 can be minimized in the three-phase reactor 5illustrated in FIG. 7. The same also applies to the embodimentillustrated in FIG. 1, including the three iron-core coils 31 to 33.

Further, FIG. 8 is a cross-sectional view of a three-phase reactoraccording to an eighth embodiment of the present invention. Athree-phase reactor 5 illustrated in FIG. 8 is generally similar to thethree-phase reactor 5 illustrated in FIG. 7. However, iron cores 41, 43,and 45 in the three-phase reactor 5 illustrated in FIG. 8 are wider thanother iron cores 42, 44, and 46. Further, the cross-sectional areas ofcoils 51, 53, and 55 wound around the iron cores 41, 43, and 45 aresmaller than those of coils 52, 54, and 56 wound around the other ironcores 42, 44, and 46.

In other words, the three-phase reactor 5 illustrated in FIG. 8 includesa first set including three iron-core coils 31, 33, and 35, and a secondset including three other iron-core coils 32, 34, and 36. Each of thefirst set and the second set alternately includes three iron-core coilsof the six iron-core coils 31 to 36. The iron-core coils arerotationally symmetrically arranged in each of the first set and thesecond set.

In the three-phase reactor 5 illustrated in FIG. 8, the dimensions ofthe iron cores, and the cross-sectional areas and winding numbers of thecoils are intended to differ between the first set and the second set.The dimensions of the gaps in the first set of the three-phase reactor 5may be intended to differ from the dimensions of the gaps in the secondset.

In the embodiment illustrated in FIG. 8, two reactors having differentproperties can be substantially included in one three-phase reactor 5.In the embodiment illustrated in FIG. 7, two reactors having the sameproperty can be included in one three-phase reactor 5. In theembodiments illustrated in FIG. 7 and FIG. 8, an installation space canbe reduced because the two reactors having the same or differentproperties can be included in one reactor. It is obvious that inductancevalues can be adjusted by connecting two reactors in series or parallelto each other. Three or more reactors having different properties or thesame properties, i.e., the three or more sets described above may beincluded in one three-phase reactor 5. It is obvious that similareffects can also be obtained in such a case.

FIG. 9 is a cross-sectional view of a three-phase reactor according to aninth embodiment of the present invention. A three-phase reactor 5illustrated in FIG. 9 is generally similar to the three-phase reactor 5described with reference to FIG. 1A, and therefore, descriptions of thethree-phase reactor 5 are omitted. As illustrated in FIG. 9, a gapmember 71 made of resin is filled into gaps 101 to 103 in thethree-phase reactor 5.

In such a case, the gap member 71 can be produced by simply filling theresin into the gaps 101 to 103, and curing the resin. Therefore, the gapmember 71 can be easily produced. A generally Y-shaped gap member 71that is similar to the gap member 71 illustrated in FIG. 9 may beproduced in advance, and may be inserted into the gaps 101 to 103instead of filling the resin. In such a case, the gap member 71suppresses vibrations of iron cores coming in contact with the gaps 101to 103, and therefore, noise generated from the iron cores can bereduced.

Further, FIG. 10 is a cross-sectional view of a three-phase reactoraccording to a tenth embodiment of the present invention. A three-phasereactor 5 illustrated in FIG. 10 is generally similar to the three-phasereactor 5 described with reference to FIG. 1A, and therefore,descriptions of the three-phase reactor 5 are omitted. As illustrated inFIG. 10, an insulating material 72 made of resin is filled into theinside of an outer peripheral iron core 20 in the three-phase reactor 5.

In such a case, the insulating material 72 can also be easily producedby simply filling the resin into the inside of the outer peripheral ironcore 20, and curing the resin. In such a case, the insulating material72 suppresses vibrations of iron-core coils 31 to 33 and the outerperipheral iron core 20, whereby generated noise can be reduced.Further, temperature equilibrium between the iron-core coils 31 to 33and the outer peripheral iron core 20 can be promoted in the embodimentillustrated in FIG. 10.

FIG. 11 is a cross-sectional view of a three-phase reactor according toan example of the present invention. Further, FIG. 12 is a top face viewof a three-phase reactor according to an example of the presentinvention. A three-phase reactor 5 illustrated in FIG. 11 and FIG. 12includes an outer peripheral iron core 20 which is generally hexagonal.The outer peripheral iron core 20 includes three outer peripheraliron-core units 24 to 26. The outer peripheral iron-core units 24 to 26come in contact with iron cores 41 to 43, or are formed integrally withthe iron cores 41 to 43, respectively. As illustrated in the drawings,the outer peripheral iron-core units 24 to 26 is formed only of straightunits.

As illustrated in FIG. 11 and FIG. 12, the outer peripheral iron core 20does not necessarily have a ring shape as long as the outer peripheraliron core 20 has a shape surrounding iron-core coils 31 to 33. Further,the outer peripheral iron core 20 having a shape other than thehexagonal shape is within the scope of the present invention. It will beobvious to those skilled in the art that some of the embodimentsdescribed above are combined as appropriate.

Further, FIG. 13A is a top face view of a three-phase reactor similar tothat of FIG. 3A. In FIG. 13A, three iron-core coils 31 to 33 in thethree-phase reactor are formed of iron cores 41 to 43 and coils 51 to53, respectively, and gaps 101 to 103 that can magnetically connect theadjacent iron-core coils 31 to 33 are formed between the adjacentiron-core coils 31 to 33. Further, the iron cores 41 to 43 includeplural iron-core units 41 a, 41 b, plural iron-core units 42 a, 42 b,and plural iron-core units 43 a, 43 b, respectively. Iron-core unit gaps131 to 133 that can magnetically connect the iron-core units are formedbetween the iron-core units.

Further, FIG. 13B is a view illustrating magnetic fluxes in thethree-phase reactor illustrated in FIG. 13A. As illustrated in FIG. 13B,there is a problem that leakage fluxes from the vicinities of theiron-core unit gaps 131 to 133 penetrate the coils 51 to 53 in thevicinities thereof, thereby causing eddy-current losses to occur in thecoils.

Further, FIG. 13C is a partially enlarged view of FIG. 13B. Asillustrated in FIG. 13C, a magnetic flux density B in sites PD, PE inthe radially outer vicinities of the coils 52, 53 is as relatively lowas 0.001 T. In contrast, a magnetic flux density B in a site PA in thegap between the adjacent iron-core units 42 a, 43 a is 0.08 T or more.Magnetic flux densities B in sites PB, PC in iron-core unit gaps 1320,1330 are also as relatively high as 0.08 T or more. In such sites,eddy-current losses occur in coils as described above.

FIG. 14A is a cross-sectional view of a three-phase reactor according toan eleventh embodiment of the present invention. Further, FIG. 14B is aperspective view of the three-phase reactor illustrated in FIG. 14A.

As illustrated in FIG. 14A and FIG. 14B, a three-phase reactor 5include: an outer peripheral iron core 20; and three iron-core coils 31to 33 that come in contact with the outer peripheral iron core 20 or arejoined to the inner surface of the outer peripheral iron core 20. InFIG. 14A, the iron-core coils 31 to 33 are arranged in the inside of theouter peripheral iron core 20 having a hexagonal shape. The iron-corecoils 31 to 33 are spaced from each other circumferentially at regularintervals in the three-phase reactor 5. The three-phase reactor 5 isrotationally symmetric. The outer peripheral iron core 20 may haveanother polygonal or ring shape.

As can be seen from the drawings, the iron-core coils 31 to 33 include:corresponding iron cores 41 to 43 that radially extend; andcorresponding coils 51 to 53 wound around the iron cores. The radiallyouter end of each of the iron cores 41 to 43 comes in contact with theouter peripheral iron core 20, or may be formed integrally with theouter peripheral iron core 20.

Further, the radially inner end of each of the iron cores 41 to 43 islocated in the vicinity of the center of the outer peripheral iron core20. In FIG. 14A and the like, the radially inner end of each of the ironcores 41 to 43 converges toward the center of the outer peripheral ironcore 20, and the front end angle of the radially inner end is about 120degrees.

In FIG. 14A, three inter-coil iron cores 81 to 83 are arranged betweenthe iron-core coils 31 to 33. Specifically, the inter-coil iron cores 81to 83 are arranged in the vicinities of the radially inner ends of theiron cores 41 to 43 of the iron-core coils 31 to 33. In FIG. 1A, theinter-coil iron cores 81 to 83 are the same shapes as each other. Thecross sections of the inter-coil iron cores 81 to 83 are pentagons ofwhich two sides are parallel to each other.

Further, a gap 101 that can magnetically connect the inter-coil ironcore 81 and the iron cores 41, 42 to each other is formed between theinter-coil iron core 81 and the iron cores 41, 42. Similarly, a gap 102that can magnetically connect the inter-coil iron core 82 and the ironcores 42, 43 is formed between the inter-coil iron core 82 and the ironcores 42, 43. A gap 103 that can magnetically connect the inter-coiliron core 83 and the iron cores 43, 41 is formed between the inter-coiliron core 83 and the iron cores 43, 41. The dimensions of the gaps 101to 103 are intended to be equal to each other. In embodiments describedlater, illustrations of the gaps 101 to 103 may be omitted.

FIG. 14C is a view illustrating magnetic fluxes in the three-phasereactor illustrated in FIG. 14A. In the present invention, as can beseen from comparisons between FIG. 14C and FIG. 13B, leakage fluxes fromthe vicinities of the gaps 101 to 103 are relatively weak, andtherefore, do not penetrate the coils 51 to 53 in the vicinities thereofvery much. Therefore, eddy-current losses are inhibited from occurringin the coils.

Further, FIG. 14D is a partially enlarged view of FIG. 14C. Magneticflux densities B in sites P1, P2 in the gap 102 in both sides of theinter-coil iron core 82 are as relatively high as 0.08 T or more. Incontrast, magnetic flux densities B in sites P3, P4 in the radiallyouter vicinities of the coils 52, 53 are as relatively low as 0.001 T.

However, sites having a magnetic flux density B of 0.08 T or more inFIG. 14D are only the sites P1, P2 in the gap 102 in both sides of theinter-coil iron core 82. Accordingly, comparisons between FIG. 14D andFIG. 13C may reveal that the number of sites in which leakage fluxes aregenerated from the vicinity of the gap 102 is small, and therefore, theleakage fluxes do not penetrate the coil 52 in the vicinity thereof verymuch. In other words, the gap 102 is formed between the iron cores 42,43 and the inter-coil iron core 82, and therefore, magnetic fluxes thathave leaked out are weak, whereby eddy-current losses occurring in thecoils 52, 53 can be suppressed. The other gaps 101 and 103 also havesimilar effects.

FIG. 15A to FIG. 15C are views that illustrate an alternative example inthe eleventh embodiment of the present invention, and that are similarto FIG. 14A. In FIG. 15A, the cross sections of inter-coil iron cores 81to 83 are rectangular, and an opening 60 is formed between theinter-coil iron cores 81 to 83. In such a case, gaps 101 to 103 aresimilar to those described above.

Further, an inter-coil iron core 84 having an equilateral-triangularshape is additionally arranged in the opening 60 in the configurationillustrated in FIG. 15B. Gaps similar to the gaps 101 to 103 are formedbetween the additional inter-coil iron core 84 and the inter-coil ironcores 81 to 83.

Further, in FIG. 15C, a single inter-coil iron core 80 is arrangedbetween iron-core coils 31 to 33. As illustrated in the drawing, thegaps 101 to 103 described above are formed between the inter-coil ironcore 80 and iron cores 41 to 43. As described above, even when thenumber of inter-coil iron cores 81 is varied, similar effects can beobtained because the gaps 101 to 103 are similar to those describedabove.

FIG. 16A is a cross-sectional view of a three-phase reactor according toa twelfth embodiment of the present invention. In FIG. 16A, the frontend angle of the radially inner end of each of iron cores 41 to 43 isabout 90 degrees. As a result, cross sections of inter-coil iron cores81 to 83 have an isosceles-triangular shape. In other words, each of theinter-coil iron cores 81 to 83 has two surfaces making an acute anglewith each other. Gaps 101 to 103 that can magnetically connect each ofthe two surfaces and the iron-core coil iron cores 41 to 43 are formedbetween each of the two surfaces and the iron-core coil iron cores 41 to43.

FIG. 16B is a view illustrating magnetic fluxes in the three-phasereactor illustrated in FIG. 16A. In the present invention, as can beseen from comparisons between FIG. 16B and FIG. 13B, the number of sitesin which leakage fluxes are generated from the vicinities of the gaps101 to 103 is small, and therefore, the leakage fluxes do not penetratecoils 51 to 53 in the vicinities thereof very much. Therefore,eddy-current losses are inhibited from occurring in the coils.

Further, FIG. 16C is a partially enlarged view of FIG. 16B. Magneticflux densities B in sites P1, P2 in the gap 102 in both sides of theinter-coil iron core 82 are as relatively high as 0.08 T or more. Incontrast, magnetic flux densities B in sites P3, P4 in the radiallyouter vicinities of the coils 52, 53 are as relatively low as 0.001 T.Sites having a magnetic flux density B of 0.08 T or more in FIG. 16C areonly the sites P1, P2 in the gap 102 in both sides of the inter-coiliron core 82. Therefore, effects similar to those described above canalso be obtained in the twelfth embodiment.

Further, in the twelfth embodiment, the cross sections of the inter-coiliron cores 81 to 83 are isosceles-triangular, and therefore, the areasof the gaps 101 to 103 are larger than those of the eleventh embodiment.Therefore, it is obvious that the twelfth embodiment is more effectivethan the eleventh embodiment. The amounts of the inter-coil iron cores81 to 83 can also be reduced.

Further, FIG. 17 is a cross-sectional view of a three-phase reactoraccording to a thirteenth embodiment of the present invention. Athree-phase reactor 5 illustrated in FIG. 17 includes: an outerperipheral iron core 20; and iron-core coils 31 to 36 similar to thosedescribed above. The iron-core coils 31 to 36 include: correspondingiron cores 41 to 46 that radially extend; and corresponding coils 51 to56 that are wound around the iron cores.

The front end angle of the radially inner end of each of the iron cores41 to 46 of the three-phase reactor 5 illustrated in FIG. 17 is about 60degrees. In FIG. 17, inter-coil iron cores 81 to 86 have the same shapeas each other. The cross sections of the inter-coil iron cores 81 to 86are pentagons of which two sides are parallel to each other. In such amanner similar to the manner described above, gaps 101 to 106 (notillustrated) that can magnetically connect the inter-coil iron cores 81to 86 and the iron cores 41 to 46 are formed between the inter-coil ironcores 81 to 86 and the iron cores 41 to 46. As described above, thethree-phase reactor 5 may include the iron-core coils 31 to 36 of whichthe number is a multiple of 3.

It is obvious that effects that are generally similar to those describedabove can also be obtained in the thirteenth embodiment. Further, in thethirteenth embodiment, the number of the iron-core coils 31 to 36 isintended to be a multiple of 3, and therefore, plural iron-core coilsexist for one phase. The cross-sectional area of each of the iron-corecoils can be reduced by connecting the plural iron-core coils inparallel to each other.

FIG. 18A is a cross-sectional view of a three-phase reactor according toa fourteenth embodiment of the present invention. Inter-coil iron cores81 to 83 in a three-phase reactor 5 illustrated in FIG. 18A include:corresponding first inter-coil iron-core units 81 a to 83 a; andcorresponding second inter-coil iron-core units 81 b to 83 b. The firstinter-coil iron-core unit 81 a and the second inter-coil iron-core unit81 b are placed side by side. The same also applies to the other firstinter-coil iron-core units 82 a, 83 a and the other second inter-coiliron-core units 82 b, 83 b.

Further, inter-coil iron-core unit gaps 131 to 133 that can magneticallyconnect the first inter-coil iron-core units 81 a to 83 a and the secondinter-coil iron-core units 81 b to 83 b are formed between the firstinter-coil iron-core units 81 a to 83 a and the second inter-coiliron-core units 81 b to 83 b. Such a gap 101 as described above (notillustrated in FIG. 18A or the like) is intended to be formed betweenthe first inter-coil iron-core unit 81 a and an iron core 41, andbetween the second inter-coil iron-core unit 81 b and an iron core 42.Other gaps 102, 103 are also intended to be similarly formed.

Further, FIG. 18B is a cross-sectional view of another three-phasereactor according to the fourteenth embodiment of the present invention.In such a case, inter-coil iron cores 81 to 83 also includecorresponding first inter-coil iron-core units 81 a to 83 a andcorresponding second inter-coil iron-core units 81 b to 83 b that areplaced side by side. The same also applies to the other first inter-coiliron-core units 82 a, 83 a and the other second inter-coil iron-coreunits 82 b, 83 b. Further, inter-coil iron-core unit gaps 131 to 133that enable magnetic connections, and such gaps 101 to 103 as describedabove are also similarly formed.

In other words, the configuration illustrated in FIG. 18A is aconfiguration in which the inter-coil iron cores 81 to 83 illustrated inFIG. 14A are divided in half by planes that is parallel to the gaps 101to 103. Further, the configuration illustrated in FIG. 18B is aconfiguration in which the inter-coil iron cores 81 to 83 illustrated inFIG. 15A are divided in half. The inter-coil iron cores 81 to 83 includethe corresponding inter-coil iron-core unit gaps 131 to 133 formedbetween the inter-coil iron-core units 81 a to 83 a and 81 b to 83 b.

Further, FIG. 18C is a cross-sectional view of still another three-phasereactor according to the fourteenth embodiment of the present invention.In the configuration illustrated in FIG. 18C, the front end units of theiron cores 41 to 43 in the configuration illustrated in FIG. 18B arereplaced with inter-coil iron cores 81 c to 83 c. Accordingly, theconfiguration illustrated in FIG. 18C includes first inter-coiliron-core units 81 a to 83 a, second inter-coil iron-core units 81 b to83 b, and the third inter-coil iron-core units 81 c to 83 c.

As can be seen from FIG. 18C, the first inter-coil iron-core units 81 ato 83 a and the second inter-coil iron-core units 81 b to 83 b haveshapes symmetrical to each other. However, the third inter-coiliron-core units 81 c to 83 c have isosceles-triangular shapes differentfrom those of the first inter-coil iron-core units 81 a to 83 a and thesecond inter-coil iron-core units 81 b to 83 b. Further, the thirdinter-coil iron-core units 81 c to 83 c come contact with neither theadjacent other inter-coil iron-core units nor iron cores 41 to 43, andgaps are formed.

As described above, in the fourteenth embodiment, both the gaps 101 to103 and the inter-coil iron-core unit gaps 131 to 133 are formed, andtherefore, the dimension of each gap per site can be reduced. As aresult, magnetic fluxes leaking out of the gaps can be reduced, andtherefore, eddy-current losses in the coils, caused by the magneticleakage fluxes, can be further reduced. It will be appreciated that eachof the inter-coil iron cores 81 to 83 may include three or moreinter-coil iron-core units arranged in a single row.

FIG. 19 is a cross-sectional view of a three-phase reactor according toa fifteenth embodiment of the present invention. Iron-core coils 31 to33 in a three-phase reactor 5 illustrated in FIG. 19 are generallysimilar to those described with reference to FIG. 14A. In the fifteenthembodiment, an outer peripheral iron core 20 includes plural, forexample, three outer peripheral iron-core units 21 to 23. The outerperipheral iron-core units 21 to 23 include iron cores 41 to 43,respectively. In FIG. 19, the outer peripheral iron-core units 21 to 23come in contact with each other. In the embodiment illustrated in FIG.19, the outer peripheral iron core 20 can be easily manufactured evenwhen the outer peripheral iron core 20 is large. In the embodimentillustrated in FIG. 17, the outer peripheral iron core 20 includesplural outer peripheral iron-core units 21 to 26.

FIG. 20 is a cross-sectional view of a three-phase reactor according toa sixteenth embodiment of the present invention. In the sixteenthembodiment, an outer peripheral iron-core unit gap 21 a that canmagnetically connect an outer peripheral iron-core unit 21 and an outerperipheral iron-core unit 22 is formed between the outer peripheraliron-core unit 21 and the outer peripheral iron-core unit 22. Similarly,outer peripheral iron-core unit gaps 21 b, 21 c that can magneticallyconnect the outer peripheral iron-core unit 22 and an outer peripheraliron-core unit 23, and the outer peripheral iron-core unit 23 and theouter peripheral iron-core unit 21, respectively, are formed between theouter peripheral iron-core unit 22 and an outer peripheral iron-coreunit 23, and between the outer peripheral iron-core unit 23 and theouter peripheral iron-core unit 21, respectively.

In other words, each of the outer peripheral iron-core units 21 to 23 isarranged through each of the outer peripheral iron-core unit gaps 21 ato 21 c. In such a case, the outer peripheral iron-core unit gaps 21 ato 21 c can be adjusted by adjusting the lengths of the outer peripheraliron-core units 21 to 23. It is obvious that as a result, an imbalancein inductances in three-phase reactor 5 can be adjusted.

A three-phase reactor 5 illustrated in FIG. 20 differs from thethree-phase reactor 5 illustrated in FIG. 19 only in view of having theouter peripheral iron-core unit gaps 21 a to 21 c. In other words, theouter peripheral iron-core unit gaps 21 a to 21 c are not formed betweenthe adjacent outer peripheral iron-core units 21 to 23 in the fifteenthembodiment. In the embodiments illustrated in FIG. 19 and FIG. 20, theouter peripheral iron core 20 can be easily manufactured even when theouter peripheral iron core 20 is large.

FIG. 21 is a cross-sectional view of a three-phase reactor according toa seventeenth embodiment of the present invention. A three-phase reactor5 illustrated in FIG. 21 is generally similar to the three-phase reactor5 illustrated in FIG. 4. However, iron cores 41, 43, and 45 in thethree-phase reactor 5 illustrated in FIG. 21 are wider than other ironcores 42, 44, and 46. Further, the cross-sectional areas of coils 51,53, and 55 wound around the iron cores 41, 43, and 45 are smaller thanthose of coils 52, 54, and 56 wound around the other iron cores 42, 44,and 46.

In other words, the three-phase reactor 5 illustrated in FIG. 21includes a first set including three iron-core coils 31, 33, and 35, anda second set including three other iron-core coils 32, 34, and 36. Eachof the first set and the second set alternately includes three iron-corecoils of the six iron-core coils 31 to 36. The iron-core coils arerotationally symmetrically arranged in each of the first set and thesecond set.

In the three-phase reactor 5 illustrated in FIG. 21, the dimensions ofthe iron cores, and the cross-sectional areas and winding numbers of thecoils are intended to differ between the first set and the second set.The dimensions of the gaps in the first set of the three-phase reactor 5may be intended to differ from the dimensions of the gaps in the secondset.

In the embodiment illustrated in FIG. 21, two reactors having differentproperties can be substantially included in one three-phase reactor 5.In the embodiment illustrated in FIG. 4, two reactors having the sameproperty can be included in one three-phase reactor 5. In theembodiments illustrated in FIG. 17 and FIG. 21, an installation spacecan be reduced because the two reactors having the same or differentproperties can be included in one reactor. It is obvious that inductancevalues can be adjusted by connecting two reactors in series or parallelto each other. Three or more reactors having different properties or thesame properties, i.e., the three or more sets described above may beincluded in one three-phase reactor 5. It is obvious that similareffects can also be obtained in such a case.

FIG. 22 is a cross-sectional view of a three-phase reactor according toan eighteenth embodiment of the present invention. A three-phase reactor5 illustrated in FIG. 22 is generally similar to the three-phase reactor5 described with reference to FIG. 14A, and therefore, descriptions ofthe three-phase reactor 5 are omitted. As illustrated in FIG. 22, a gapmember 71 made of resin is filled into gaps 101 to 103 in thethree-phase reactor 5.

In such a case, the gap member 71 can be produced by simply filling theresin into the gaps 101 to 103, and curing the resin. Therefore, the gapmember 71 can be easily produced. A gap member 71 having a shape similarto the shape of the gap member 71 illustrated in FIG. 22 may be producedin advance, and may be inserted into the gaps 101 to 103 instead offilling the resin. In such a case, the gap member 71 suppressesvibrations of iron cores coming in contact with the gaps 101 to 103, andinter-coil iron cores 81 to 83, and therefore, noise generated from theiron cores can be reduced. The gap members 71 may be an insulatingmaterial.

Further, FIG. 23 is a cross-sectional view of a three-phase reactoraccording to a nineteenth embodiment of the present invention. Athree-phase reactor 5 illustrated in FIG. 23 is generally similar to thethree-phase reactor 5 described with reference to FIG. 14A, andtherefore, descriptions of the three-phase reactor 5 are omitted. Asillustrated in FIG. 23, an insulating material 72 made of resin isfilled into the inside of an outer peripheral iron core 20 in thethree-phase reactor 5. The insulating material 72 may be a gap member.

In such a case, the insulating material 72 can also be easily producedby simply filling the resin into the inside of the outer peripheral ironcore 20, and curing the resin. In such a case, the insulating material72 suppresses vibrations of iron-core coils 31 to 33, the outerperipheral iron core 20, and inter-coil iron cores 81 to 83, wherebygenerated noise can be reduced. Further, temperature equilibrium betweenthe iron-core coils 31 to 33, the outer peripheral iron core 20, andinter-coil iron cores 81 to 83 can be promoted in the embodimentillustrated in FIG. 23.

FIG. 24A and FIG. 24B are cross-sectional views of three-phase reactorsaccording to still another embodiment of the present invention. FIG. 24Aand FIG. 24B are the views that are generally similar to FIG. 3A andFIG. 3B, and therefore, redundant descriptions thereof are omitted. Thesame also applies to the other drawings.

In FIG. 24A and FIG. 24B, three inter-coil iron cores 81 to 83 arearranged between iron cores 41 to 43 in iron-core coils 31 to 33.Specifically, the inter-coil iron cores 81 to 83 are arranged in thevicinities of the radially inner ends of the iron cores 41 to 43.Further, a gap 101 that can magnetically connect the inter-coil ironcore 81 and the iron cores 41, 42 is formed between the inter-coil ironcore 81 and the iron cores 41, 42. The same also applies to the otherinter-coil iron cores 82, 83.

In such a case, both the gaps 101 to 103 and iron-core unit gaps 111 to113 are formed, and therefore, the dimension of each gap per site can bereduced. It is obvious that as a result, magnetic fluxes leaking out ofthe gaps can be reduced, and therefore, eddy-current losses in thecoils, caused by the magnetic leakage fluxes, can be reduced.

Further, FIG. 25 is a cross-sectional view of a three-phase reactor,similar to that in FIG. 4, according to a still other embodiment of thepresent invention. Iron-core coils 31 to 33 in a three-phase reactor 5illustrated in FIG. 25 includes: iron cores 41′ to 43′ that radiallyextend; and coils 51 to 53 wound around the iron cores. Three inter-coiliron cores 81 to 83 are arranged between the iron cores 41′ to 43′.Further, a gap 101 that can magnetically connect the inter-coil ironcore 81 and the iron cores 41, 42 is formed between the inter-coil ironcore 81 and the iron cores 41, 42. The same also applies to the otherinter-coil iron cores 82, 83.

In such a case, both the gaps 101 to 103 and outer peripheral iron-coregaps 121 to 123 are formed, and therefore, the dimension of each gap persite can be reduced. Further, the effect of inhibiting heat generatedfrom the iron-core coils from being transferred to outer peripheral ironcores can be obtained.

FIG. 26 is a view illustrating a machine or device including athree-phase reactor of the present invention. In FIG. 26, a three-phasereactor 5 is used in a motor driving device. The machine or the deviceincludes such a motor driving device.

FIG. 27 is a view illustrating another machine or device including athree-phase reactor of the present invention. In FIG. 27, a three-phasereactor 5 is included in a power conditioner. The machine or the deviceincludes such a power conditioner.

It is obvious that in such a case, a motor driving device or the likeincluding the three-phase reactor 5 can be easily provided. Combinationsof some of the embodiments described above as appropriate are within thescope of the present invention.

Advantageous Effects of Invention

In the first aspect of the present invention, differences in magneticpath lengths between phases are small in comparison with reactors havingconventional structures, and therefore, an imbalance in inductances,caused by the differences in the magnetic path lengths, can be reduced.Further, most of the at least three iron-core coils are surrounded bythe outer peripheral iron core, and therefore, the rate of magneticfields generated from the coils and leaking out to the outside of theouter peripheral iron core can be reduced. Further, the gaps havingoptional thicknesses can be inexpensively disposed, and therefore, thereactor is more advantageous in view of design than reactors havingconventional structures. Further, the reactor has a structure in whichthe gaps are disposed to obtain inductances, and therefore, controlwinding is unnecessary. Therefore, the three-phase reactor can be formedto be lightweight and simple.

In the second aspect of the present invention, the number of theiron-core coils is intended to be a multiple of 3, and therefore, theplural iron-core coils exist for one phase. The cross-sectional area ofeach of the iron-core coils can be reduced by connecting the pluraliron-core coils in parallel to each other. The winding number of each ofthe iron-core coils can be reduced by connecting the plural iron-corecoils in series to each other.

In the third aspect of the present invention, both the gaps between theiron-core coils and the iron-core unit gaps between the plural iron-coreunits are formed, and therefore, the dimension of each gap per site canbe reduced. As a result, magnetic fluxes leaking out of the gaps can bereduced, and therefore, eddy-current losses in the coils, caused by themagnetic leakage fluxes, can be reduced.

In the fourth aspect of the present invention, the outer peripheraliron-core gaps are formed between the outer peripheral iron core and theiron-core coils, and therefore, heat generated from the iron-core coilsis inhibited from being transferred to the outer peripheral iron core.

In the fifth embodiment of the present invention, the outer peripheraliron core is divided into plural units, and therefore, the outerperipheral iron core can be easily manufactured even when the outerperipheral iron core is large.

In the sixth aspect of the present invention, an imbalance ininductances can be easily adjusted by adjusting the outer peripheraliron-core unit gaps.

In the seventh aspect of the present invention, an imbalance ininductances caused by the arrangement of the at least three iron-corecoils can be minimized.

In the eighth aspect of the present invention, two reactors can beincluded in one reactor, and therefore, an installation space can bereduced when two reactors are preferred. Inductance values can beadjusted by connecting the reactors in parallel or series to each other.

In the ninth aspect of the present invention, three or more reactors canbe included in one reactor, and therefore, an installation space can bereduced when three or more reactors are preferred. Inductance values canbe adjusted by connecting the three or more reactors in parallel orseries to each other.

In the tenth aspect of the present invention, vibrations of the ironcores coming in contact with the gaps can be suppressed, and noisegenerated from the iron cores can be reduced.

In the eleventh aspect of the present invention, temperature equilibriumbetween the iron-core coils and the outer peripheral iron core can bepromoted, and noise generated from the iron-core coils and the outerperipheral iron core can be reduced.

In the twelfth aspect of the present invention, the gaps are formedbetween the iron-core coils and the inter-coil iron cores, andtherefore, each gap per site is narrower than that in the case of theabsence of the inter-coil iron cores. Therefore, magnetic fluxes leakingout are small. Because the distances between the gaps and theinter-coils are long, magnetic fluxes penetrating the coils furtherbecome small, eddy currents generated in the coils are reduced, andtherefore, eddy-current losses occurring in the coils can be reduced.

In the thirteenth aspect of the present invention, because the areas ofthe gaps are increased, the magnetic flux densities of the gaps aredecreased, thereby decreasing magnetic fluxes leaking out, magneticfluxes penetrating the coils become small, and therefore, eddy-currentlosses occurring in the coils can be further reduced.

In the fourteenth aspect of the present invention, the number of theiron-core coils is intended to be a multiple of 3, and therefore, theplural iron-core coils exist for one phase. The cross-sectional area ofeach of the iron-core coils can be reduced by connecting the pluraliron-core coils in parallel to each other. The winding number of each ofthe iron-core coils can be reduced by connecting the plural iron-corecoils in series to each other.

In the fifteenth aspect of the present invention, both the gaps betweenthe iron-core coils and the iron-core unit gaps between the pluraliron-core units are formed, and therefore, the dimension of each gap persite can be reduced. As a result, magnetic fluxes leaking out of thegaps can be reduced, and therefore, eddy-current losses in the coils,caused by the magnetic leakage fluxes, can be reduced.

In the sixteenth aspect of the present invention, the outer peripheraliron-core gaps are formed between the outer peripheral iron core and theiron-core coils, and therefore, heat generated from the iron-core coilsis inhibited from being transferred to the outer peripheral iron core.

In the seventeenth aspect of the present invention, both the gapsbetween the iron-core coils and the inter-coil iron-core unit gaps areformed, and therefore, the dimension of each gap per site can bereduced. As a result, magnetic fluxes leaking out of the gaps can bereduced, and therefore, eddy-current losses in the coils, caused by themagnetic leakage fluxes, can be further reduced.

In the eighteenth aspect of the present invention, the outer peripheraliron core is divided into plural units, and therefore, the outerperipheral iron core can be easily manufactured even when the outerperipheral iron core is large.

In the nineteenth aspect of the present invention, an imbalance ininductances can be easily adjusted by adjusting the outer peripheraliron-core unit gaps.

In the twentieth aspect of the present invention, an imbalance ininductances caused by the arrangement of the at least three iron-corecoils can be minimized.

In the twenty-first aspect of the present invention, two reactors can beincluded in one reactor, and therefore, an installation space can bereduced when two reactors are preferred. Inductance values can beadjusted by connecting the reactors in parallel or series to each other.

In the twenty-second aspect of the present invention, three or morereactors can be included in one reactor, and therefore, an installationspace can be reduced when three or more reactors are preferred.Inductance values can be adjusted by connecting three or more reactorsin parallel or series to each other.

In the twenty-third aspect of the present invention, vibrations of theiron cores coming in contact with the gaps, and the inter-coil ironcores can be suppressed, and noise generated from the iron cores can bereduced.

In the twenty-fourth aspect of the present invention, temperatureequilibrium between the iron-core coils, the outer peripheral ironcores, and the inter-coil iron cores can be promoted, and noisegenerated from the iron-core coils, the outer peripheral iron cores, andthe inter-coil iron cores can be reduced.

In the twenty-fifth to twenty-eighth aspects of the present invention,the motor driving device including the reactor, the machine includingsuch a motor driving device, the power conditioner including thereactor, and the machine or device including such a power conditionercan be easily provided.

Although the present invention has been described with reference to theexemplary embodiments, persons skilled in the art will understand thatthe changes described above as well as various other changes, omissions,and additions may be made without departing from the scope of thepresent invention.

1. A three-phase reactor comprising: an outer peripheral iron core; andat least three iron-core coils that come in contact with an innersurface of the outer peripheral iron core or are joined to the innersurface, wherein the at least three iron-core coils comprisecorresponding iron cores and corresponding coils wound around the ironcores; each of the iron cores extends only in a radial direction of theouter peripheral iron core; the three-phase reactor further comprises atleast one inter-coil iron cores arranged between the at least threeiron-core coils; and gaps that can magnetically connect the at leastthree iron-core coils and the inter-coil iron cores to each other areformed between the at least three iron-core coils and the inter-coiliron cores.
 2. The three-phase reactor according to claim 1, whereineach of the inter-coil iron cores comprises two surfaces making an acuteangle with each other; and the two surfaces face the correspondingiron-core coils across the corresponding gaps.
 3. The three-phasereactor according to claim 1, further comprising additional inter-coiliron cores arranged between the inter-coil iron cores, and wherein gapsthat can magnetically connect the additional inter-coil iron cores andthe inter-coil iron cores are formed between the additional inter-coiliron core and the inter-coil iron cores.
 4. The three-phase reactoraccording to claim 1, wherein the number of the at least three iron-corecoils is a multiple of
 3. 5. The three-phase reactor according to claim1, wherein the iron cores of the at least three iron-core coils comprisea plurality of iron-core units; and iron-core unit gaps that canmagnetically connect the plurality of iron-core units are formed betweenthe plurality of iron-core units.
 6. The three-phase reactor accordingto claim 5, wherein the coil includes a plurality of coils wound aroundthe iron-core units.
 7. The three-phase reactor according to claim 1,wherein outer peripheral iron-core gaps that can magnetically connectthe iron cores of the at least three iron-core coils and the outerperipheral iron core to each other are formed between the iron cores ofthe at least three iron-core coils and the outer peripheral iron core.8. The three-phase reactor according to claim 1, wherein the inter-coiliron core comprises inter-coil iron-core units, inter-coil iron-coreunit gaps that can magnetically connect the plurality of inter-coiliron-core units are formed between the plurality of inter-coil iron-coreunits.
 9. The three-phase reactor according to claim 1, wherein theouter peripheral iron core comprises a plurality of outer peripheraliron-core units.
 10. The three-phase reactor according to claim 9,wherein outer peripheral iron-core unit gaps are formed between twoadjacent outer peripheral iron-core units of the plurality of outerperipheral iron-core units.
 11. The three-phase reactor according toclaim 1, wherein the at least three iron-core coils are rotationallysymmetrically arranged.
 12. The three-phase reactor according to claim1, wherein a gap member, insulating paper, or resin which is anon-magnetic material is inserted or filled into the gaps of thethree-phase reactor.
 13. The three-phase reactor according to claim 1,wherein a gap member, insulating paper, or resin which is a non-magneticmaterial is inserted or filled inside of the outer peripheral iron coreof the three-phase reactor.
 14. The three-phase reactor according toclaim 1, wherein the outer peripheral iron core comprises at least threeouter peripheral iron-core units; wherein one part of an inside face ofthe outer peripheral iron-core unit is partially parallel to a side faceof the iron core; wherein each of the coils is arranged in a spaceformed between the one part of the inside face of the outer peripheraliron-core unit and the side face of the iron core, and wherein a gaplength of the gap between the one iron core and the adjacent iron coreis shorter than a width of the space.
 15. A three-phase reactorcomprising: an outer peripheral iron core including at least three outerperipheral iron-core units; and at least three iron-core coils that arearranged inside of the outer peripheral iron core, wherein each of theat least three iron-core coils comprise iron cores that come in contactor are integral with each of the outer peripheral iron-core units andcoils wound around the iron cores; gaps that can magnetically connectone iron-core coil of the at least three iron-core coils and aniron-core coil adjacent to the one iron-core coil to each other areformed between the one iron-core coil of the at least three iron-corecoils and the iron-core coil adjacent to the one iron-core coil; whereinone part of an inside face of the outer peripheral iron-core unit ispartially parallel to a side face of the iron core; wherein each of thecoils is arranged in a space formed between the one part of the insideface of the outer peripheral iron-core unit and the side face of theiron core, and wherein a gap length of the gap between the one iron coreand the adjacent iron core is shorter than a width of the space.
 16. Thethree-phase reactor according to claim 15, wherein each of radiallyinside ends of the iron core converge on a center of the outerperipheral iron core.